The effects of Al on the calcium currents in Helix neurons.

1. The effects of aluminium (Al) on calcium (Ca) currents were investigated by using the conventional two-electrode voltage clamp technique in Helix pomatia neurons. The peak amplitude, kinetics, and voltage dependence of activation and inactivation of the Ca currents were studied in the presence of 10(-5)-10(-3) M AlCl3, at pH 6. 2. Al prolonged the rising phase of the Ca currents and therefore increased the time to peak at each command voltage step used. 3. There was no significant influence of Al on the peak amplitude of the Ca currents, but the voltage dependence of the time to peak, activation, and inactivation of the Ca currents shifted to more positive potentials as a consequence of Al treatment. 4. The leak currents were not influenced by Al up to 1 mM, which was the maximal dose applied. 5. The results support the suggestion that Al may modify the Ca homeostasis and that it exerts a neurotoxic effect, at least in part, by modulation of the Ca current of the neuronal membrane.